Aerospike Java Async library seems stuck

I am executing a udf using aeropike async client. The client has been initialized as:-

    try {
        asyncClientPolicy.maxThreads = 40;
        asyncClientPolicy.asyncMaxCommands = 20;
        asyncClientPolicy.maxSocketIdle = 13;
        asyncClientPolicy.asyncMaxCommandAction = MaxCommandAction.BLOCK;
        asyncClientPolicy.asyncSelectorThreads = 7;
        asyncClientPolicy.asyncTaskThreadPool = Executors.newFixedThreadPool(20, new ThreadFactory() {
            public final Thread newThread(Runnable runnable) {
                Thread thread = new Thread(runnable);
                thread.setDaemon(true);
                return thread;
            }
        });
    }

So I have 20 threads to handle the callbacks. After a while I see that my program is not doing any progress, indicating deadlock/starvation. Jstack gives me following result:-

java.lang.Thread.State: WAITING (parking)
    at sun.misc.Unsafe.park(Native Method)
    - parking to wait for  <0x000000064048f338> (a java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
    at java.util.concurrent.locks.LockSupport.park(LockSupport.java:186)
    at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:2043)
    at java.util.concurrent.ArrayBlockingQueue.take(ArrayBlockingQueue.java:374)
    at com.aerospike.client.async.AsyncCluster$BlockBufferQueue.getByteBuffer(AsyncCluster.java:114)
    at com.aerospike.client.async.AsyncCluster.getByteBuffer(AsyncCluster.java:68)
    at com.aerospike.client.async.AsyncCommand.execute(AsyncCommand.java:59)
    at com.aerospike.client.async.AsyncClient.execute(AsyncClient.java:949)
    at main.java.labs.RuleEngineAerospikeConnection.updatePositiveSegmentsUDF(RuleEngineAerospikeConnection.java:217)
    at main.java.labs.Segment$ProductChecker.onSuccess(Segment.java:346)
    at com.aerospike.client.async.AsyncRead.onSuccess(AsyncRead.java:149)
    at com.aerospike.client.async.AsyncCommand.finish(AsyncCommand.java:293)
    at com.aerospike.client.async.AsyncSingleCommand.read(AsyncSingleCommand.java:59)
    at com.aerospike.client.async.AsyncCommand.run(AsyncCommand.java:261)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
    at java.lang.Thread.run(Thread.java:745)

I have exactly 20 threads in waiting state all on execute command. Am I doing something wrong with the setup, because I expect the client to return, even if there is any exception in my UDF, what happens if there is an infinite loop? could it lead to this behavior?